A functional unit of this type for a vehicle interior is known in general in the form of a loading-space covering for station wagons. This type of loading-space covering has a covering tarpaulin which is held in a manner such that it can be wound up and unwound on a winding shaft mounted in a cassette housing. On its end region which is in front in the extension direction, the covering tarpaulin is provided with a dimensionally stable extension bar which has end regions protruding laterally over the side edges of the covering tarpaulin. The end regions can be positioned in guide rails laid horizontally just below a sill line of the vehicle interior. In the longitudinal direction of these guide rails, the end regions can be displaced transversely with respect to a longitudinal axis of the extension rod, and the end regions are therefore arranged in a longitudinally movable manner. As a result, it is possible to guide the extension rod in a defined manner during an extension or retraction movement of the covering tarpaulin. Longitudinal movements, i.e. in particular displacement movements, lead, between the end regions of the extension rod and the guide rails in the vehicle interior, to a sliding resistance which increases the manual operating forces when extending the covering tarpaulin.